For the two pre-specified secondary efficacy endpoints, the study showed that the time to severe flare was significantly delayed in patients receiving belimumab administered subcutaneously plus SoC (170 days, p=0.0003) compared with those on placebo plus SoC (116.5 days). In addition, in patients receiving more than 7.5 mg/day of prednisone (n=503), 18.2% of patients receiving belimumab administered subcutaneously plus SoC in the study were able to reduce their steroid dose by 25% or more to <7.5 mg/day during Weeks 40-52, compared with 11.9% of those on placebo plus SoC, but this did not reach statistical significance (p=0.0732).

“Despite use of current standard of care, such as glucocorticosteroids and immunosuppressants, about 60% of lupus patients continue to experience persistent symptoms and severe disease flares,” said Paul-Peter Tak, Senior Vice-President and Head of the Immuno-Inflammation Therapy Area Unit at GSK. “This is GSK’s third successful Phase III study of belimumab in patients with lupus, the results of which reinforce our belief in the BLyS pathway as a means of reducing underlying disease activity. On the basis of these data, we expect to progress towards global regulatory filings for a belimumab subcutaneous formulation, which if approved, will provide appropriate patients with a new approach to treatment administration.”

Incidence of AEs leading to discontinuation in the belimumab administered subcutaneously plus SoC group was 7.2% compared with 8.9% with placebo plus SoC. The percentage of patients experiencing a serious AE was 10.8% with belimumab administered subcutaneously plus SoC compared with 15.7% with placebo plus SoC. A total of 5 deaths were reported; three (0.5%) with belimumab administered subcutaneously plus SoC, and two (0.7%) with placebo plus SoC. The overall incidence of death in all the randomized controlled studies of belimumab in lupus was 0.7% for the belimumab group, which is similar to that in the placebo group (0.5%).

Belimumab subcutaneous formulation is currently not approved for use anywhere in the world.